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Public Model Question Paper 2019 - 2020

12th Standard EM

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Biology

Time : 02:45:00 Hrs
Total Marks : 70

    Part I

    Answer all the questions.

    Choose the most suitable answer from the given four alternatives and write the option code with the corresponding answer.

    15 x 1 = 15
  1. Fusion of morphologically and physiologically similar gametes is called ______

    (a)

    anisogamy

    (b)

    hologamy

    (c)

    isogamy

    (d)

    merogamy

  2. Select the incorrect action of hormonal contraceptive pills from the following

    (a)

    Inhibition of spermatogenesis.

    (b)

    Inhibition of ovulation

    (c)

    Changes in cervical mucus impairing its ability to allow passage and transport of sperms

    (d)

    Alteration in uterine endometrium to make it unsuitable for implantation

  3. Watson and Crick proposed their double helical DNA model based on the X-ray diffraction analysis of _________

    (a)

    Erwin Chargaff

    (b)

    Meselson and Stahl

    (c)

    Wilkins and Franklin

    (d)

    Griffith

  4. Darwin’s finches are an excellent example of

    (a)

    connecting links

    (b)

    seasonal migration

    (c)

    adaptive radiation

    (d)

    parasitism

  5. Select the correct statement from the following

    (a)

    Primary treatment of sewage involves biological oxidation

    (b)

    Excreta of cattle is commonly called Gobur

    (c)

    Delta endotoxin of Bacillus thuringiensis is encoded by pen-genes

    (d)

    Trichoderma is a free-timing bacteria very common in root ecosystem

  6. Some organisms are able to maintain homeostasis by physical means _______

    (a)

    Conform

    (b)

    Regulate

    (c)

    Migrate

    (d)

    Suspend.

  7. 1000 fish in the volume of water in the pond indicates _____________________

    (a)

    Relative abundance

    (b)

    Ecological density

    (c)

    Crude density

    (d)

    Population density

  8. Statement 1: Primary sporogenous cell functions as megaspore mother cell.
    Statement 2: Megaspore mother cell undergoes mitotic division producing megaspores.

    (a)

    Statement 1 is correct and statement 2 is incorrect.

    (b)

    Statement 1 is incorrect and statement 2 is correct.

    (c)

    Both the statements 1 and 2 are correct.

    (d)

    Both the statements 1 and 2 are incorrect.

  9. Match list I with list II
     

    List I list II
    A. A pair of chromosomes extra with diploid i) monosomy
    B. One chromosome extra to the diploid ii) tetrasomy
    C. One chromosome loses from diploid iii) trisomy
    D.Two individual chromosomes lose from diploid

    iv) double monosomy

    (a)

    A-i, B-iii, C-ii, D-iv

    (b)

    A-ii, B-iii, C-iv, D-i

    (c)

    A-ii, B-iii, C-i, D-iv

    (d)

    A-iii, B-ii, C-i, D-iv

  10. Statement 1: Pairing of homologous chromosome is called as syndesis.
    Statement 2: Proterminal synapsis occurs from telomeres.

    (a)

    Statement 1 is correct and Statement 2 is incorrect

    (b)

    Statement 1 is incorrect and Statement 2 is correct

    (c)

    Both the statements are correct

    (d)

    Both the statements are incorrect

  11. Micro propagation involves

    (a)

    vegetative multiplication of plants by using micro-organisms.

    (b)

    vegetative multiplication of plants by using small explants.

    (c)

    vegetative multiplication of plants by using microspores.

    (d)

    Non-vegetative multiplication of plants by using microspores and megaspores.

  12. Statement 1: Ephemerals are drought evaders.
    Statement 2: They are not true xerophytes.

    (a)

    Statement 1 is correct. Statement 2 is incorrect.

    (b)

    Statement 1 is incorrect. Statement 2 is correct.

    (c)

    Both the statements are correct.

    (d)

    Both the statements are incorrect

  13. Identify the correct sequence of various zones from surface to depth in a pond ecosystem.

    (a)

    Profundal, limnetic, littoral and benthic

    (b)

    Benthic, littoral, profundal and limnetic

    (c)

    Limnetic, profundal, littoral and benthic

    (d)

    Littoral, limnetic, profundal and benthic

  14. Who is celebrated as Forest Man of India?

    (a)

    Anand Mohan Chakrabarthy

    (b)

    Dr. M.S. Swaminathan

    (c)

    Jadav Molai Payeng

    (d)

    Choudhary Ram Dhan

  15. Observe the following statements and pick out the right option from the following:
    Statement I: The drug sources of Siddha include plants, animal parts, ores and minerals.
    Statement II: Minerals are used for preparing drugs with long shelf-life.

    (a)

    Statement I is correct

    (b)

    Statement II is correct

    (c)

    Both statements are correct

    (d)

    Both statements are wrong

  16. Part II

    Answer any 6 questions. Question no. 24 is compulsory.

    6 x 2 = 12
  17. Mention the different modes of asexual reproduction.

  18. What is colostrum? Write its significance.

  19. Complete the equation.
    (a) Phenylalanine \(\underrightarrow { A } \) Tyrosine
    (b) DOPA \(\underrightarrow { B } \) Melanin

  20. What makes the DNA and RNA as acidic molecules?

  21. Which is the primary lymphoid organs of.birds? Mention its location and role.

  22. What is Albedo effect and write their effects?

  23. What will happen if all producers are removed from ecosystem?

  24. What does NCB stands for? Mention its role.

  25. What are interferons? Mention their role.

  26. Part III

    Answer any 6 questions. Question no. 33 is compulsory.

    6 x 3 = 18
  27. How does Mutation theory of De Vries differ from Lamarck and Darwin’s view in the origin of new species.

  28. Write the key features of organic farming.

  29. Differentiate Natality and Mortality

  30. Write a note on Sacred Groves.

  31. Why does the zygote divides only after the division of Primary endosperm cell.

  32. Compare Mendelian factors with chromosome.

  33. What are the adverse effects of temperature on plant?

  34. How do forests help in maintaining the climate?

  35. In 1926, Vavilov initially proposed eight main geographic centres of crop origin. Mention any six of them.

  36. Part IV

    Answer all the questions.

    5 x 5 = 25
    1. Suggest a solution to water crisis and explain its advantages.

    2. Give a detailed account on anyone fibe yielding plant.

    1. Point out any five morphological adaptations of epiphytes.

    2. Draw a pyramid from following details and explain in brief.
      Quantities of organisms are given-Hawks-50, plants-1000.rabbit and mouse-250 +250, pythons and lizard- 100 + 50 respectively.

    1. Describe incomplete dominance exhibited by Mirabilis jalapa.

    2. Give an account on Cryopreservation.

    1. Explain the mechanism of lac-operon of the E-coli.

    2. What is endosperm. Explain the types.

    1. Identify the given image and label its parts marked as a, b, c and d

    2. How are STDs transmitted?

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